Telephone service providers typically use network interface devices (NIDS) to provide telephone service to their customers. The network interface device typically connects the inside wiring of the customer's premises, such as the internal telephone wiring in a customer's home, to the telephone network. The network interface device often has two “sides,” one to the central office of the telephone service provider and one to the customer's telephone lines. Typical network interface devices include a protective enclosure and passive circuitry with terminal blocks and line protectors. Analog signals typically pass through the network interface device unmodified except for hazardous voltages, such as lightning, which are clamped by the line protectors.